GSSAPI or Generic Security Service Application Programming Interface allows login to an SSH server via alternative mechanisms such as Kerberos.
It's useful for those that need the feature but if you're just using the normal password or public key authentication method, it could just unnecessarily slow the overall login process.
Related: How to speed up SSH authentication
You can disable (or enable) GSSAPI authentication for SSH via GSSAPIAuthentication directive in your SSHd configuration.
Specifies whether user authentication based on GSSAPI is allowed. The default is no.
$ sudo vi /etc/ssh/sshd_config [sudo] password for user:
Add the line if it doesn't already exist and remove the # at the beginning of the line if existing line starts with a #.
$ sudo systemctl restart sshd
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